Network Troubleshooting

A network administrator attempts to configure Core-Switch-01 to serve as the Spanning Tree Protocol (STP) root bridge for VLAN 50. The administrator executes the command to set the bridge priority for VLAN 50 to 61440. Shortly after, a newly provisioned access switch with factory default settings is connected to the network and unexpectedly assumes the root bridge role for VLAN 50. Which of the following best explains why the access switch became the root bridge instead of Core-Switch-01?

A network technician provisions a new database server on VLAN 50 ($10.50.0.0/24$). Upon booting up, running `ip addr show` reveals that the host interface has acquired an IP address of $169.254.88.12/16$. The technician manually assigns a static address of $10.50.0.50/24$ to the interface and verifies that the host can successfully ping its default gateway at $10.50.0.1$. The centralized DHCP server resides on VLAN 10 ($10.10.0.5/24$).

Which of the following are the MOST likely causes of the host initially receiving an APIPA address? (Select TWO.)

A system administrator is troubleshooting an inability to establish a secure remote administration session via SSH to a Linux server located at $192.168.1.50$. The administrator executes the command `netstat -an` directly on the server to inspect active network socket states and receives the following truncated output:

Proto Local Address Foreign Address State
TCP 0.0.0.0:23 0.0.0.0:0 LISTENING
TCP 0.0.0.0:80 0.0.0.0:0 LISTENING
TCP 0.0.0.0:443 0.0.0.0:0 LISTENING

Based on the utility output, which condition explains why remote SSH connections to this server are failing?

A network technician is investigating a report that a Windows client workstation cannot load an internal intranet application hosted on a distant subnet (`172.16.10.50`). The technician decides to perform a bottom-up command-line diagnostic workflow to isolate the point of failure. In what sequence should the technician execute the following commands to logically isolate the issue from local IP configuration to remote network path routing?

A network administrator is troubleshooting an issue where workstations assigned to VLAN 30 on Switch-1 cannot communicate with servers on VLAN 30 attached to Switch-2. An audit of interface GigabitEthernet0/1 on Switch-1 reveals that it was mistakenly configured with static access mode (`switchport mode access`). Additionally, the trunk configuration documentation indicates VLAN 30 must be explicitly allowed, but the interface allowed list is currently restricted to VLANs 10 and 20 (`switchport trunk allowed vlan 10,20`).

Which TWO configuration commands must the administrator execute on Switch-1 interface GigabitEthernet0/1 to establish an 802.1Q trunk link and permit VLAN 30 traffic to pass across it?

A network administrator is troubleshooting an existing Category 6 UTP cabling run between a floor switch and a wall outlet. Although a basic wiremapper confirms full pin-to-pin continuity and proper TIA/EIA 568B wire map alignment, connected devices experience frequent Frame Check Sequence (FCS) errors and link degradation during heavy traffic. Which of the following diagnostic tools should the administrator use to locate the exact position of the physical cable damage along the run?

A network administrator deploys a new workstation on VLAN 35 ($10.35.0.0/24$). Upon booting up, the workstation cannot access internal servers or the internet. Executing `ipconfig /all` on the workstation yields the following output:

IPv4 Address. . . . . . . . . . . : 169.254.14.88
Subnet Mask . . . . . . . . . . . : 255.255.0.0
Default Gateway . . . . . . . . . :
DHCP Enabled. . . . . . . . . . . : Yes

The central DHCP server is located on VLAN 10 ($10.10.0.0/24$) and actively provides IP address leases to clients on VLAN 10. Which of the following represents the most likely cause of this issue?

A network technician is investigating performance issues on several newly installed cabling runs connecting a distribution switch to server racks. The technician needs to identify appropriate diagnostic procedures and remedies for physical layer faults. Which of the following actions and tool selections correctly resolve these physical layer problems? (Select TWO.)

A network administrator is troubleshooting an issue where a newly connected Linux host receives an IP address via DHCP but cannot communicate with hosts on external subnets. Arrange the following diagnostic and troubleshooting steps into the correct chronological order according to standard Network+ troubleshooting methodology.

A network administrator is conducting a comprehensive network analysis on a workstation experiencing connectivity and resolution issues. Match each command-line utility command on the left with its primary diagnostic function on the right.

A network administrator is troubleshooting connectivity for a workstation on a newly configured VLAN 25 ($172.16.25.0/24$). The central DHCP server is located on VLAN 10 ($172.16.10.100$). Running `ipconfig /all` on the workstation yields the following output snippet:

IPv4 Address. . . . . . . . . . . : 169.254.88.12
Subnet Mask . . . . . . . . . . . : 255.255.0.0
Default Gateway . . . . . . . . . :
DHCP Server . . . . . . . . . . . :

Which of the following is the most likely cause of this issue?

Match each switch log message or port status indicator on the left with its corresponding root cause on the right.

A network technician is troubleshooting a high optical insertion loss issue on a 10Gbps multimode fiber optic link connecting two distribution switches. An optical power meter indicates a lower-than-expected power level, but no complete signal break is detected along the cable span. The technician suspects physical contamination on the connector ferrule. Which tool should the technician use to visually inspect the connector end-face for microscopic dirt, scratches, or oil?

A network administrator is troubleshooting an issue where client machines on the subnet $10.0.50.0/24$ cannot establish connections to an internal HTTPS portal hosted at $10.0.50.200$. The administrator runs the `netstat -an` utility directly on the destination server hosting the portal and receives the following output snippet:

Active Connections

Proto Local Address Foreign Address State
TCP 0.0.0.0:80 0.0.0.0:0 LISTENING
TCP 0.0.0.0:443 0.0.0.0:0 LISTENING
TCP 10.0.50.200:443 10.0.50.45:51204 ESTABLISHED
UDP 0.0.0.0:500 *:*

To verify local network layer mapping on a client machine ($10.0.50.45$) that is experiencing intermittent timeouts, which command-line utility should the technician use to inspect the cached IP-to-MAC address bindings?

A network technician is troubleshooting a performance issue on a newly installed network switch port connected to a high-volume server. Monitoring tools report low overall throughput, a high count of frame check sequence (FCS) errors, and a constantly incrementing late collision counter on the switch port interface. The interface status shows the link is operational at 100 Mbps. Which of the following is the most likely cause of this issue?

Match each physical layer cabling issue or task with the diagnostic tool best suited to identify or resolve it.

A network administrator is investigating a name resolution issue where workstations can reach an internal server via IPv4, but fail to resolve its IPv6 address using the internal DNS server at $10.0.10.5$. The administrator needs to query the specified DNS server directly to verify if an IPv6 mapping exists for `app.lab.internal`.

Which TWO of the following command-line diagnostic utilities and syntax options will successfully query the targeted DNS server specifically for the host's IPv6 ($AAAA$) record? (Select TWO)

A network administrator is troubleshooting an 802.1Q trunk link between Switch-A and Switch-B. Host computers on VLAN 20 attached to Switch-B are unable to communicate with the default gateway located on Switch-A. Inspection of the trunk configuration reveals two issues: Switch-A is configured with native VLAN 20 while Switch-B is configured with native VLAN 1, and VLAN 20 is currently missing from the allowed VLAN list on Switch-B's trunk interface. Which TWO of the following statements accurately explain the technical causes of the communication failure in this setup? (Select TWO.)

A network technician is troubleshooting a newly installed Category 6A UTP cable run that is failing performance certification tests due to excessive Near-End Crosstalk (NEXT). A visual inspection of the patch panel terminations reveals that all eight conductors are connected to their corresponding pin positions according to the T568B standard. Which of the following installation flaws is the most likely cause of the excessive NEXT?

A network technician is troubleshooting connectivity for a VoIP desk phone on VLAN 80 ($10.80.0.0/24$). The phone boots up and receives an IP address lease, but it cannot register with the central PBX server located on VLAN 10 ($10.10.0.10/24$). Running a network status command on the phone reveals the following output:

text
IPv4 Address . . . . . . . . . . . : 10.80.0.45
Subnet Mask . . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . . : 10.80.1.1
DHCP Server . . . . . . . . . . . . : 10.80.0.1
DHCP Option 066 (TFTP Server) . . . : 10.10.0.10

Which of the following is the primary cause of the registration failure?